I have posted below on our store. We have pedestals in there to cool the grain with extractors on them and extractors in the evaes to take the warm air out of the building. We've not dried all of it and it was very hot (for here) when we cut the first lot which as at the back of the building and that was 20 degrees C on Monday, still having been cut in the beginning of August.

If you store anything other than grain in there you will get mice. They hide under anything you put in there so resist the temptation to store anything other than grain in the grain store.